Design For Thin Bar Laser And Experiment Study On Ionization

Againsted the requirements of laser ionization experiment in air, in this paper, developed a Q-switched Nd:YAG laser amplifier system, whose master oscillator's operation material was large slenderness ratio (φ4.2mm×130mm). The output pulse of the system was 15ns, the output energy was 805.9mJ , the angle of divergence was 2mrad , the peak power was 68.4 MW/cm~2, and the system magnification was 2.5. When pump energy and operation material volume were constant, theoretical and experimental results showed selecting large slenderness ratio operation material can help the output energy increase.In this paper, physical model of laser ionization in air,plasma channel formation mechanism,ionization characteristics,detection method of plasma ,as well as the technology of electrical field imposed on the beam were studied. Making use of developed nanosecond pulse laser proceeded laser air breakdown experiment. Through imposing electrical field on nanosecond pulse laser beam,changing electric pole range interval, implemented the laser air breakdown. Tested and measured the data in different conditions, and drawed the curve of power density of laser,electrical-field intensity,the length of ionization. Theoretical and experimental results showed that when increasing the power density of laser and gradually decreasing electrical field imposed on beam, was still able to obtain identical ionization length. When the power density of laser was 508.6 MW/cm~2 and electric voltage was 53KV, could obtain 8cm length ionization.